1. Field of the Invention
The present invention relates to electrodes attachable to a patient, and in particular to such electrodes for use with medical monitoring and diagnostic equipment.
2. Description of the Prior Art
Electrodes in various forms which can be attached to the skin of a patient for providing a means for obtaining various electrical signals from the patient for supply to medical monitoring and diagnostic devices are known in the art. One such electrode is disclosed in U.S. Pat. No. 4,141,366 in the form of a tape with a porous backing material, a conductive layer on one side thereof, covered by a layer of adhesive material.
Another such electrode is disclosed in U.S. Pat. No. 4,102,331 having a foam pad impregnated with conductive gel, and having an adhesive layer for attachment to the skin of a patient. This electrode must be utilized with a separately applied electrically conductive gel. Another electrode is disclosed in U.S. Pat. No. 3,805,769 having self-contained conductive material for providing an electrical connection between the monitoring equipment and the skin of a patient. This electrode must also, however, be utilized with an electrically conductive gel separately applied in a relatively complex ten-step process.
An electrode is disclosed in U.S. Pat. No. 3,565,059 having a normally dry electroconductive material which when wetted with a solvent exhibits adhesive properties for attachment to the skin of a patient. An electrode is disclosed in U.S. Pat. No. 2,943,628 having a laminate construction including a base layer with an adhesive coating on one side and two overlying conductive discs.
The above conventional electrodes exhibit two primary disadvantages, one disadvantage being in the method required to assemble the electrodes, and the other being in the method of applying the electrodes to the patient.
None of the above electrodes can be manufactured from a number of continuous webs of material comprising the different layers which can be continuously fed through an assembly machine in overlying fashion. All of the above conventional electrodes during assembly require one or more stamping or cutting steps, with the subsequent necessity of accurately aligning or superimposing the cut pieces in order to achieve an assembled electrode. The necessity for cutting and subsequent alignment not only complicates the assembly process, but also slows the process in contrast to a continuous feed process.
The second disadvantage of the above electrodes is the necessity for the use of separately-applied conductive gel, or "wet" conductive gel contained within the electrode. The use of separately-applied conductive gel to the area of the patient's skin to which the electrode is to be attached not only adds a step to the attachment of the electrode to the patient, but also requires a supply of such conductive gel always be available. Those electrodes having self-contained wet conductive gel have a limited shelf life before drying out.